1. Field of the Invention
The present invention is generally related to a fuel delivery system for a marine engine and, more particularly, to a fuel system that includes a portable fuel tank with an internal pump that regulates the pressure of fuel pumped from the portable tank through a flexible conduit to a marine engine.
2. Description of the Prior Art
Portable fuel tanks have been used in conjunction with marine engines, such as outboard motors, for many years. Typically, fuel is drawn from the portable fuel tank by a vacuum created within a flexible hose connecting the fuel tank to the outboard motor. Under the cowl of the outboard motor, a lift pump typically draws the fuel from the portable fuel tank and provides the fuel, under pressure, to the internal combustion engine of the outboard motor. This arrangement has been used in conjunction with carbureted engines and fuel injected engines.
A serious problem can occur when a fuel pump of an outboard motor is used to draw fuel from a fuel tank. Particularly in hot weather, the fuel can vaporize and, especially under the influence of lower pressures at the inlet of the fuel pump, the fuel delivery system can experience vapor lock. Vapor lock is a familiar problem to users of outboard motors and refers to the inability of a fuel pump to draw liquid fuel to its inlet because of the presence of fuel vapor within the fuel line.
The use of a portable fuel tank in conjunction with an outboard motor is very well known to those skilled in the art.
U.S. Pat. No. 4,594,970, which issued to Baars et al on Jun. 17, 1986, describes a marine installation including a fuel/oil mixing device. The installation comprises a marine propulsion device including a propulsion unit having a lower unit supporting a propeller and a power head including a two-stroke internal combustion engine having an apparatus for feeding a fuel/oil mixture to the engine and including a fuel/oil mixture pump having an inlet and being operable to create suction at the inlet, a flexible hose releasably connected to and communicating with the inlet of the fuel/oil mixture pump, and a remote tank having an interior providing a fuel reservoir.
U.S. Pat. No. 4,784,104, which issued to Dimond on Nov. 15, 1988, discloses a fuel line with an integral coaxial return line. The fuel system for an internal combustion engine has a fuel pump communicating with a fuel tank and delivering fuel to a fuel monitoring device and including a device for detecting and returning excess for vaporized fuel to the tank. The system is provided with a return fuel line for returning the detected vaporized or excess fuel to the tank with at least a portion of the return fuel line coaxial with and contained within the supply line.
U.S. Pat. No. 4,848,283, which issued to Garms et al on Jul. 18, 1989, discloses a marine engine with a combination vapor return, crankcase pressure, and cooled fuel line conduit. A marine propulsion system includes a two cycle water cooled crankcase compression internal combustion engine including a vapor separator, a remote fuel tank, and a fuel pump in the tank for delivering fuel to the engine in response to crankcase pulse pressure. A combination conduit between the fuel tank and the engine includes a first passage communicating crankcase pulse pressure from the engine to the fuel pump in the tank, a second passage supplying fuel from the pump in the tank to the engine, a third passage returning fuel vapor from the vapor separator at the engine back to the tank, a fourth passage supplying cooling water from the engine towards the tank, and a fifth passage returning water from the fourth passage back to the engine.
U.S. Pat. No. 4,911,203, which issued to Garms on Mar. 27, 1990, describes a fuel line connector. A coupling assembly for connecting conduits conveying fuel under pressure, utilizes a pair of seals so as to define a chamber for the containment of excess pressurized fuel during the disengagement of the coupling members. A protective shield or flange is provided around the locking mechanism so as to prevent inadvertent contact with the release mechanism and accidental disengagement of the coupling members.
U.S. Pat. No. 2,656,828, which issued to Conover on Oct. 27, 1953, describes a fuel supplying means using a crankcase pressure developed in a two-cycle engine for delivering fuel to the carburetor. A fuel tank, which is separate from the powerhead of an engine, and connected therewith for use, is readily separated from the powerhead for independent transportation. The weight of the outboard motor as such is greatly reduced, thus facilitating transportation and mounting and dismounting.
Certain types of pumps are referred to by those skilled in the art as "Gerotors" pumps. Various types of Gerotor pumps are described in detail in patents that issued to Quintilian. For example, U.S. Pat. No. 2,672,825, which issued to Quintilian on May 23, 1954, describes a hydraulic pump and motor. Similarly, U.S. Pat. No. 2,672,824, which also issued on Mar. 23, 1954, describes a hydraulic pump or motor. U.S. Pat. No. 2,753,810, which issued to Quintilian on Jul. 10, 1956, also describes a pump or motor. U.S. Pat. No. 2,872,872, which issued to Quintilian on Feb. 10, 1959, describes a hydraulic pump or motor. As will be described below in greater detail in the description of the preferred embodiment, certain types of Gerotor pumps are particularly applicable for use in conjunction with the present invention.
The patents described above are hereby explicitly incorporated herein.
If a fuel pump could be satisfactorily contained within a portable fuel tank, many problems relating to vapor lock would be eliminated. As a result, other components normally contained under the cowl of an outboard motor could be eliminated since some of those components have a primary function of eliminating or minimizing vapor lock. It would therefore be significantly beneficial if a portable fuel tank could be provided with a pump within the fuel tank in a way that satisfactorily provides fuel to a marine engine, minimizes the likelihood of vapor lock problems, and reduces the overall cost of the marine engine system.